U.S. Pat. No. 4,589,052 describes an electronic trip unit for molded case circuit breakers wherein the trip function is provided by means of an integrated circuit chip. U.S. Pat. No. 4,649,455 describes a rating plug circuit wherein the rating of the breaker can be adjusted over a wide operating range by selection of an appropriate burden resistor.
U.S. patent application Ser. No. 862,929 filed May 14, 1986 entitled "Trip Actuator for Molded Case Circuit Breakers" describes an electromagnetic actuator that interfaces between the trip unit electronics and the circuit breaker operating mechanism to separate the circuit breaker contacts in response to overcurrent conditions.
U.S. patent application Ser. No. 882,989 filed July 7, 1986 entitled "Combined Trip Unit and Accessory Module for Electronic Trip Circuit Breakers" describes an accessory module which is accessible from the circuit breaker cover and which allows convenient access to the electromagnetic actuator for selection of various accessory options.
All the aforementioned U.S. Patents and Patent Applications are incorporated herein for purposes of reference and should be reviewed for the specific teachings contained therein.
As described within the aforementioned U.S. Pat. No. 4,649,455, it is possible to select the resistance value of the burden resistor within the circuit breaker electronics for setting the circuit breaker rating. The use of such an adjustable rating plug, is governed by strict electrical industry standards, since it is important that the proper rating plug be inserted within the appropriate circuit breaker in order for the circuit breaker to operate properly. One such requirement mandates that the circuit breaker will either trip or default to its lowest rating when the rating plug is removed from the circuit breaker enclosure. A further requirement is that some tool must be required for removing the rating plug from the circuit breaker to deter inadvertent or negligent removal thereof.
One purpose of this invention is to describe a rating plug enclosure which subscribes to the electrical industry standards while providing ready access to the rating plug burden resistors mounted on the rating plug printed circuit board.